1. Field of the Invention
The present invention relates to a process for the separation of a basic amino acid from a fermentation broth using cation exchange resins.
2. Description of the Background
At present, basic amino acids are mainly produced by fermentation and, cation exchange resins are generally utilized for separating the basic amino acid from its fermentation broth. The use of the cation exchange resin generally entails an adsorption step in which a fermentation broth adjusted to a definte pH is brought into contact with a strongly acidic salt-type cation exchange resin such as ammonium-type one to adsorb a basic amino acid thereto and, an elution step in which the basic amino acid is eluted with an eluting agent such as ammonia water, and the cation exchange resin is regenerated into salt-type one. By repeating these two steps, the basic amino acid is separated from its fermentation broth.
One of the problems with the cation exchange resin step is that, at present, large quantities of water must be used. Namely, a fermentation broth and then washing water are fed into the resin tower in order to completely pass the fermentation broth through the cation exchange resin layer at the adsorption step. Similarly, at the elution step, washing water must be fed in order to completely pass the eluting agent. Further, suspended matters, etc. contained in the fermentation broth at the adsorption step accumulate in the cation exchange resin layer and, large quantities of washing water must be used to remove the accumulated solid. These not only increase the consumption amount of water but also increase the amount of liquid discharged. In addition, the concentration of the basic amino acid in the eluate is low and accordingly, much energy is required for condensing the eluate.
Various methods for reducing the amount of washing water to be used and energy required for condensation have been explored. Some of these methods have substituted various discharged liquids for the washing water such as, for example, the method described in Japanese Published Unexamined Patent Applications 12879/1975 and 11173/1977. However, these methods are quite complex and, therefore, increase production costs. Therefore, when using cation exchange resins in separating basic amino acids from solutions containing the same, it would be particularly desirable to be able to greatly reduce the amount of washing water used as well as to be able to greatly reduce the energy required for condensation of the eluate. However, to date, such a separation process has remained unknown.
Therefore, a need continues to exist for a process for the separation of a basic amino acid from a liquid containing the same using cation exchange resins which utilizes a reduced quantity of washing water and much less energy for the condensation of the eluate.